When I was in grade school we used to build model airplanes out of kits. The frame was made out precut pieces of balsa wood, each having been carefully pinned according to the plans along a preprinted arc to obtain the appropriate curvature, and then cemented, piece to piece, with airplane glue. The fuselage was made out of tissue paper, first glued to the balsa frame, trimmed, then dampened with water to shrink it taut, and finally, when dry, lacquered and painted to make it stiff and realistic. The engine was merely a long rubber band that ran the internal length of the fuselage, from propeller block at the nose to tail, wound up by rotating the propeller many times and then let loose to unwind for a flight of perhaps ten seconds at best. If you were a really ambitious model builder you followed the instructions very carefully: you were supposed to sand off any excess glue on the frame so as leave no imperfections at all.